The invention relates to the load-bearing bonded fitting of windshields onto the windshield window aperture flange of motor-vehicle bodies by means of a bead of adhesive comprising rapidly setting synthetic material applied between the inside windshield surface and the window aperture flange. German published unexamined patent application 35 00 205 discloses an arrangement of this type which the present invention is directed toward improving.
The motor vehicles produced today have the front windshield, and also the rear windows or windshield, bonded along the entire circumference of the windshield or window directly to the windshield or window flange of the window aperture of the motor-vehicle body. This generally takes place nowadays by means of an adhesive layer designed as a strand or bead of adhesive between the edge regions of the windshield or window surface which is on the inside and the windshield or window flange of the window aperture, as can be seen, for example, from German published unexamined patent applications 34 09 903 and 35 00 205 and from German patent document DE-C 35 01 490.
It is already known from the prior art to arrange a cavity in the bead of adhesive (German application 35 00 205) or, at the same time as the bead of adhesive is applied, to install a flexible cord into the latter (German application 34 09 903), in order to simplify the cutting-out of the windshield or window should the car windshield or rear window need to be removed at a later date when repairing the motor vehicle and/or should the windshield or rear window need to be replaced. However, in the meantime, the use of cutting tools which are equipped with cutters oscillating at high frequency has largely gained acceptance in practice when removing windshields or windows bonded into the motor vehicle bodies (see German patent documents DE-C 33 04 981 and DE-C 33 24 676). In this arrangement, when removing the windshield or window, the bead of adhesive arranged between the windshield or window and the windshield or window flange is normally cut through along the entire circumference of the windshield or window by the cutters.
However, when cutting out the windshields in this manner using the cutting tools there is the problem that the relatively short cutters of the cutting tools can only reach the bead of adhesive in the lower corners of the windshield with difficulty. This problem has hitherto been avoided when designing the motor vehicles by bevelling the lower corners of the windshield in a manner which is favorable for the cutters of the cutting tools to reach them, so as to make the windshield accessible for repair. This led, however, to unattractive, stylistic compromises when realizing the design of the body in the region of the A-pillar of the motor vehicle. Moreover, the problem of manipulating the cutting tools always gave rise to the risk of the paintwork of the motor vehicle body being scratched.
An underlying object of the invention is therefore to provide the load-bearing bonded fitting for windshields, the use of which no longer incurs the disadvantages described above and, accordingly, the windshields can be realized solely with the design of the body in mind.
This object is achieved according to the invention by providing an arrangement comprising a load-bearing bonded fitting of a windshield onto a windshield flange of a window aperture of a motor vehicle body, comprising a bead of adhesive formed of rapidly setting synthetic material applied between an inside windshield surface and a windshield flange, and a pressure-sensitive adhesive strip attached between the windshield and the bead of adhesive at each of two lower corners of the windshield, said pressure-sensitive adhesive strip having respective adhesive sides facing the inside windshield surface and being permanently flexible, said pressure-sensitive adhesive strip at the two lower corners of the windshield serving to accommodate removal of the windshield without requiring cutting of the bead of adhesive in the region of the two lower corners where the bead of adhesive is covered by the respective pressure-sensitive adhesive strips.
The bonded fitting according to the invention means that it is no longer necessary to cut through the regions of the bead of adhesive in the lower corners of the windshield using the cutter. The adhesive bonding of the pressure-sensitive adhesive strip is less capable of bearing a load and it is merely this which is effective in the lower corner regions of the windshield. When removing the windshield--after the bead of adhesive has been cut through along the rest of the circumference of the windshield--the relatively short regions of the pressure-sensitive adhesive strip can be detached from the windshield without great use of force by careful, manual tilting of the rest-of the windshield, which has been cut free, forwards out of the interior of the vehicle around the lower edge of the windshield.
The pressure-sensitive adhesive strip which bears on the bead of adhesive is preferably designed such that it is wider than the width of the bead of adhesive where the bead is present in a pressed-flat state in the region of the pressure-sensitive adhesive strip.
The bead of adhesive consists of an adhesive generally used in the motor-vehicle industry comprising a two-pack or single-pack polyurethane adhesive or polysulphide adhesive which sets in atmospheric moisture. Alternatively, the bead of adhesive comprises a butyl rubber adhesive.
According to certain preferred embodiments, the pressure-sensitive adhesive strip comprises, with the exception of the pressure-sensitive adhesive, a closed-cell strip of foam made of a permanently flexible plastic.
In order to ensure that the pressure-sensitive adhesive strip has a long service life, in particular in order to protect it against the effect of UV radiation from the atmosphere, UV stabilizers are advantageously added to the material of the pressure-sensitive adhesive strip in certain preferred embodiments.
As described above, in order to remove bonded windshields or windows, the bead of adhesive arranged between the windshield or window and the windshield or window flange is cut through along the entire circumference of the windshield or window by oscillating cutters. Since when cutting out in this manner the relatively short cutters can only reach the bead of adhesive in the lower corners of the windshield with difficulty, in particular if the lower corners are designed such that they are stylistically attractive in the region of the A-pillar of the motor vehicle, it is proposed above to design the bond such that it does not pose a problem when carrying out repair work by providing, in each of the two lower corners of the windshield, a respective pressure-sensitive adhesive strip between the windshield and the bead of adhesive, which is designed such that it is permanently flexible in its wall thickness and faces the inner windshield surface with its adhesive side, the pressure-sensitive adhesive strip preferably extending from the corners in each case for approximately 60 to 120 mm along the lower and the side edges of the windshield. This measure aims to obtain, in the lower corner regions of the windshield, an adhesive bonding of the pressure-sensitive adhesive strip which is less capable of bearing a load and has the result that, after the bead of adhesive has been cut through along the entire circumference of the windshield, when removing the windshield and while carefully and manually tilting the windshield out of the interior of the vehicle around the lower edge of the windshield, the pressure-sensitive adhesive strips are intended to be ripped open and hence also the bonded joint is intended to be severed there. The pressure-sensitive adhesive strip which bears on the-bead of adhesive is preferably designed such that it is wider than the width of the bead of adhesive when the bead is in a pressed-flat state. The pressure-sensitive adhesive strip is preferably composed of a strip of closed-cell foam made of a permanently flexible plastic.
It has also been learned that it is difficult to realize a bond in the corner regions which, on the one hand, is indeed less capable of bearing a load but, on the other hand, is absolutely watertight and which can be readily severed without destroying the windshield when tilting and pressing out the latter. It is especially difficult to realize such a bond if the corner regions, which are designed separately for bonding purposes, are of somewhat longer dimensions, i.e., approximately 100 mm or more per limb or branch from the corner. The corner bonds which have not been cut free could therefore be more stable than the windshield when commercially available strips of foam were used and, as a result, the windshield could break, as in prior arrangements without the pressure-sensitive strips at the lower corners of the window.
It is therefore a further object of the invention to develop the separately designed bond of the corner regions to such an extent that the corner bonds do indeed, on the one hand, become detached in every case when manually pressing out the rest of the windshield which has been cut free, without exerting force on the windshield, but, on the other hand, that the window-pane bond is permanently watertight even in the corner region.
This last mentioned object is achieved according to preferred embodiments of the invention by providing further features. A first feature is to provide the-pressure-sensitive adhesive strip with adhesion reducing material at its side facing the bead of adhesive. A second feature is to provide a strip-shaped track of pressure-sensitive adhesive on the side of the pressure-sensitive strip facing the window, which track is narrower than the pressure-sensitive strip. Embodiments are also contemplated which include a combination of these last mentioned features. According to these features the intention is for a pressure-sensitive adhesive strip to be used which has an adhesive or bonding force which is reduced at least on one side in order to ensure reliable detachment of the bond in the corner region, but on the other hand the adhesive or bonding action has in all cases to be sufficiently effective to permanently and completely prevent water from penetrating through the bonded joint, for example, due to a capillary or creeping action.
Other objects, advantages, and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.